7299

TYR

tyrosinase;TYR;tyrosinase

LB24-AB|SK29-AB|monophenol monooxygenase|oculocutaneous albinism IA|tumor rejection antigen AB

11q14.3

protein-coding

The relationship between the disease course and the prognostic relevance of sequential tyrosinase reverse transcription-PCR assay in the peripheral blood of advanced metastatic melanoma patients was ascertained. The clinical usefulness of tyrosinase in stage IV melanoma patients is still debated, owing to the wide range of variability (positive expression from 30 up to 100% of patients) and the possibility of a transient shedding of melanoma cells into the bloodstream. A total of 200 consecutive stage IV metastatic patients treated at our department were included, 149 with active metastatic disease undergoing systemic therapies (group A), and 51 disease free after surgery (group B). For each patient, a baseline sample was obtained within 3 weeks of either the clinical/radiological demonstration of metastatic disease or the surgical treatment; thereafter, tyrosinase determinations were performed at day 1 of each therapy course before chemotherapy administration or at each follow-up visit. Tyrosinase expression was determined using standard reverse transcription-PCR nested techniques. A baseline positive determination was obtained in 72.5% of the patients with active metastatic disease (group A) but not in any of the patients who were disease free after surgery (group B). Therapy administration induced an early clearance of circulating melanoma cells, from 72.5 to 44.9% at the second down to 29.5% at the third determination. Tyrosinase expression before the third cycle was significantly associated with the clinical response: 56/81 (69.1%) patients with a negative tyrosinase determination obtained a response or a stable disease, whereas 29/34 (85.3%) patients with a positive test developed a progressive disease (P<0.001). A clinical response was observed in all the patients who had a negative tyrosinase at the first three determinations, although all patients whose first three determinations were positive developed a progressive disease. Multivariate analysis showed that baseline tyrosinase status carries an independent prognostic value on both overall survival and time to progression; moreover, tyrosinase results during follow-up were entered as time-dependent covariates in a multivariate analysis and were shown to be the most significant prognostic parameter associated to both overall survival and time to progression. In particular, the presence of a constant positive expression during follow-up was associated with the development of new metastatic sites in 95.6% of patients with active metastatic disease. Our results demonstrate that the discrepancies in the positive tyrosinase rates reported in the literature are related to the disease status at the time of sampling and to chemotherapy administration. Tyrosinase expression in the peripheral blood both at baseline and during follow-up can be considered a reliable prognostic parameter associated with the response to treatment, development of new metastatic sites, time to progression and survival.

BACKGROUND: Detection of melanoma cells in peripheral blood is a promising method for monitoring haematogenous spread of melanoma cells. It enables us to detect early metastasis and to better stratify candidates for adjuvant immunotherapy. Inconsistent data on the sensitivity and clinical relevance of this method have been reported. STUDY DESIGN: We developed a multimarker real-time reverse transcription-PCR (RT-PCR) for quantification of five melanoma markers: Melan-A, gp100, MAGE-3, MIA and tyrosinase. In this prospective study, 65 patients with resected cutaneous melanoma stage IIB-III were screened. Peripheral blood samples were collected every 3 months for the following 18 months, and circulating melanoma cells were examined and compared with clinical staging results. RESULTS: Eighteen patients relapsed during the trial and showed different types of melanoma progression. All these patients experienced statistically significant tumour marker elevation in the period from 0 to 9 months before the disease progression. MAGE-3 was the most sensitive progression marker. In patients with progression, we observed three concordant positive markers in 39% of cases, two concordant positive markers in 28%, and finally one marker in 33%. CONCLUSIONS: This report describes a multiple-marker real-time RT-PCR, which is able to provide quantitative data on melanoma markers in the peripheral blood of melanoma patients. Measurement of the studied molecular markers in our hands represents a prognostic factor and a useful method for early detection of metastasis and treatment response of melanoma patients.